Lubrication structure for a manual transmission

ABSTRACT

A lubrication structure for a manual transmission having a control housing disposed on an upper portion of the transmission case and within which a control shaft is installed. An open portion leading to the control housing is formed in an upper portion of the transmission case, and at least one oil drain hole for discharging oil having entered the control housing through the open portion is formed near the open portion. Therefore, oil in the control housing is discharged to an oil guide through the oil drain hole, and the oil is prevented from being discharged through the air breather, so an efficient lubrication structure can be obtained.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority of Korean Application No. 10-2003-0056447, filed Aug. 14, 2003, the disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a lubrication structure for a manual transmission, and more particularly, to a lubrication structure in which an oil passageway is formed in a control housing to improve lubrication efficiency and to prevent an oil leak through an air breather.

BACKGROUND OF THE INVENTION

Generally, a manual transmission is installed between a clutch and a drive shaft, and it plays a role to increase or decrease rotational force of an engine according to the driving state of the vehicle. The manual transmission also has a reversing device for driving the vehicle backward.

In general, a manual transmission includes a drive shaft and a driven shaft for transmitting rotational power. Shift gears, meshed with each other to transmit shift power, are coupled to the drive shaft and the driven shaft. A plurality of bearings are disposed among the drive shaft, the driven shaft, the shift gears, and transmission case thereby facilitating rotation of the shafts and the shift gears.

For smooth operation of the shafts, the shift gears, and the bearings, lubricant oil for lubricating and cooling frictional portions is needed, so a specific amount of lubricant oil must be stored within the transmission case. The lubricant oil stored in the transmission case is scattered around the circumference thereof by rotation of the shift gears so that the lubricant oil is supplied to the frictional portions.

In such manual transmissions, an air breather is typically installed in an upper portion of the transmission case so that a pressure inside the transmission case can be dissipated. However, in such prior manual transmissions, lubricant oil that is scattered by the shift gears within the transmission case flows into a control housing where the air breather is installed, and the lubricant oil entering the control housing stays there. If the lubricant oil continually enters the control housing, the lubricant oil can be discharged to outside through the air breather. Such dispersion of oil into the environment is undesirable.

Further, although an oil guide can be provided within the transmission case in order to more uniformly supply the lubricant oil, the lubricant oil entering the control housing is not suitably dispersed so that an efficient lubrication structure cannot be obtained.

The information disclosed in this Background of the Invention section is only for enhancement of understanding of the background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art that is already known to a person skilled in the art.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a lubrication structure for a manual transmission in which an oil drain hole is formed in a control housing so that oil therein is discharged to an oil guide through the oil drain hole. Oil is thereby prevented from being discharged through the air breather and efficient lubrication is obtained.

In a lubrication structure for a manual transmission according to a preferred embodiment of the present invention, the manual transmission has a control housing that is disposed on an upper portion of a transmission case and within which a control shaft is installed. An open portion leading to the control housing is formed in an upper portion of the transmission case, and at least one oil drain hole for discharging oil having entered the control housing through the open portion is formed near the open portion.

It is preferable that an air breather is installed in an upper portion of the control housing.

It is also preferable that an oil guide is provided inside the transmission case, and wherein one of the at least one oil drain hole is formed at a position where the oil passing through the oil drain hole is discharged to the oil guide.

It is preferable that the at least one oil drain hole comprises two oil drain holes that are formed respectively on both sides of the open portion.

Preferably, one of the at least one oil drain hole is formed under the air breather.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate an embodiment of the invention, and, together with the description, serve to explain the principles of the invention, where:

FIG. 1 is a perspective view of a manual transmission with a lubrication structure according to an embodiment of the present invention;

FIG. 2 is a front view of the manual transmission of FIG. 3;

FIG. 3 is a perspective view showing a state of the manual transmission of FIG. 1 in which a control housing is opened;

FIG. 4 is a perspective view of a cut-away main portion of the lubrication structure of a manual transmission according to an embodiment of the present invention; and

FIG. 5 is a sectional view along a line A-A of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Referring to FIG. 1, a clutch housing 30 in which a clutch is installed is coupled to a front side of a transmission case 20. A control housing 40, where a control shaft 50 is installed, is coupled to an upper portion of case 20. An air breather 60, for dissipating pressure inside the transmission case 20, is installed on an upper portion of the control housing 40.

Referring to FIG. 2, oil that is scattered by gears 15 disposed within the transmission case 20 is supplied to various lubrication portions inside the transmission case 20, and the oil also flows into the control housing 40. Reference numeral 17 denotes an oil guide for guiding the scattered oil to a specific portion inside the transmission case 20.

As shown in FIG. 3, a coupling portion 21, to which the control housing 40 is coupled, is provided at an upper portion of the transmission case 20. An open portion 22, leading to the control housing 40, is formed on an upper portion of the transmission case 20 inside the coupling portion 21. A control finger and a shift lug (not shown) are connected to the control shaft 50 through the open portion 22, so that operating force of the control shaft 50 can be transmitted to a shift rail. Two oil drain holes 25 and 26 are formed near open portion 22, so that the oil having entered the control housing 40 through the open portion 22 from the inside of the transmission case 20 can return to the inside of the transmission case 20 through the oil drain holes 25 and 26. As shown in FIG. 3, the oil drain holes 25 and 26 may be formed on plates 41 and 43 that are disposed on each side of the open portion 22.

As shown in FIG. 5, one oil hole 25 of the two oil holes 25 and 26 is formed at a position in which the oil passing through the oil hole 25 is exhausted to the oil guide 17.

Although in this embodiment the two oil holes 25 and 26 are formed on both sides of the open portion 22, the number of oil holes can be more than two or less than two according to design conditions.

Hereinafter, operation of a lubrication structure for a manual transmission according to an embodiment of the present invention will be explained.

Referring again to FIG. 3, the oil that is scattered by rotational force of the gears 15 disposed inside the transmission case 20 is supplied to various rotating frictional portions and the inside of the control housing 40 through an inner wall of the transmission case 20 and the like. High-pressure air due to friction heat that is generated by operation of the transmission is discharged into the outside through the air breather 60 after passing the inner space of the control housing 40.

The oil, having entered the control housing 40 through the open portion 22 of the transmission case 20, gathers at a lower portion by its weight, and the gathered oil then drops to the oil guide 17 through the oil drain hole 25. In addition, because the oil drain hole 26 is formed as a concave-convex portion 23 under a portion where the air breather 60 is installed, the oil inside the control housing 40 is discharged into the transmission case 20 through the oil drain hole 26 instead of being discharged to the outside through the air breather 60.

Thus, according to embodiments of the present invention, a plurality of oil drain holes are formed in the control housing, so that pressure inside the transmission can be effectively discharged through the air breather and simultaneously oil having entered the control housing drops to the oil guide without being discharged through the air breather with the air, thereby obtaining an efficient lubrication structure.

Although preferred embodiments of the present invention have been described in detail hereinabove, it should be clearly understood that many variations and/or modifications of the basic inventive concepts herein taught which may appear to those skilled in the present art will still fall within the spirit and scope of the present invention, as defined in the appended claims. 

1. A lubrication structure for a manual transmission having a control housing that is disposed on an upper portion of a transmission case and within which a control shaft is installed, wherein an open portion leading to the control housing is formed in an upper portion of the transmission case, and wherein at least one oil drain hole for discharging oil having entered the control housing through the open portion is formed near the open portion.
 2. The lubrication structure of claim 1, wherein an air breather is installed in an upper portion of the control housing.
 3. The lubrication structure of claim 1, wherein an oil guide is provided inside the transmission case, and wherein one of the at least one oil drain hole is formed at a position where the oil passing through the oil drain hole is discharge to the oil guide.
 4. The lubrication structure of claim 1, wherein the at least one oil drain hole comprises two oil drain holes that are formed respectively on both sides of the open portion.
 5. The lubrication structure of claim 2, wherein one of the at least one oil drain hole is formed under the air breather. 